Types of TweetDeck columns and what they display:

• Home: Timeline for one of your accounts
• Search: A column for a specific search term
• Followers: Follow activity for all your accounts or one specific account
• Tweets: Tweets from a specific account
• Mentions : Only includes when users mention a specific account
• Messages: Direct messages for a specific account
• Mentions (All Accounts): Only includes when users mention a specific account
• Messages (All Accounts): Direct messages for a specific account
• Activity: What’s happening with the accounts you follow
• Inbox: Direct messages from all your authorized accounts in aggregate
• User:
• Favorites: Tweets marked as favorites from a specific account
• Trending: A column dedicated to specific worldwide trends
• Lists: Assign or create a list to be displayed within a column
• Collection:s A timeline of curated Tweets, hand-selected by you, that you can share with others
• Scheduled: Your scheduled Tweets

https://support.twitter.com/articles/20169914-tweetdeck-columns#